Immunologic approaches to cancer management have focussed in recent years on attempts to identify and isolate human tumor-associated antigens which will prove clinically useful in the immunodiagnosis of cancer. While it is well known in theory that malignant tumors can be detected by radioimmunoassay (RIA) techniques for associated cell-surface antigens, the theory is limited in its practical clinical application to malignant tumors for which specific cell-surface antigens are available in highly purified form; also, these antigens must be released into the bloodstream, and the determinants must retain antigenicity when radiolabelled. Further, clinical utility of the RIA in cancer management is dependent upon biological fluid levels of the selected antigen which substantially correlate with tumor burden; utility is further enhanced if the selected antigen is site-specfic, i.e., associated with tumors of specific organs.
As a result of the difficulties encountered in attempting to isolate and study a protein for which no function or activity is known, and for which the method of isolation relies on the presumption that it is more prevalent in tumor tissues than in normal tissues, satisfactory clinical antigenic markers have not been heretofore characterized for many malignant tumors, in particular, human lung tumors.